Re: [Qemu-devel] [PATCH 1/4] block: Make bdrv_drain_invoke() recursive

[Eric Blake <eblake@redhat.com>]

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On 12/05/2017 08:54 AM, Kevin Wolf wrote:
> This change separates bdrv_drain_invoke(), which calls the BlockDriver
> drain callbacks, from bdrv_drain_recurse(). Instead, the function
> performs its own recursion now.
> 
> One reason for this is that bdrv_drain_recurse() can be called multiple
> times bdrv_drain_recurse(),

Doesn't read right.  Should the second instance be changed to 'by
itself', or is the correct meaning something else?

> but the callbacks may only be called once.
> The separation is necessary to fix this bug.
> 
> The other reasons is that we intend to go to model where we call all

s/reasons/reason/

> driver callbacks first, and only then start polling. This is not fully
> achieved yet with this patch, as bdrv_drain_invoke() contains a
> BDRV_POLL_WHILE() loop for the block driver callbacks which can still
> call callbacks for any unrelated event. It's a step in this direction
> anyway.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/io.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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